Infant With Vomiting and Weight Loss

[Ann Emerg Med. 2008;52:496.]

A 5-week-old boy presented to the emergency department with a 3-day history of vomiting and weight loss. He was an only child, with an uneventful full-term birth history. Systems review and family history were unremarkable. On examination, the infant was somnolent but when offered a bottle, fed vigorously, promptly vomiting projectile, nonbilious/nonbloody vomitus. His laboratory analysis was significant for a potassium level of 3.6 mEq/L and a chloride level of 95 mEq/L.

Infantile hypertrophic pyloric stenosis. Infantile hypertrophic pyloric stenosis is the most common cause of intestinal obstruction in infancy, with an incidence of 2 to 4 per 1000 live births.1 Infantile hypertrophic pyloric stenosis occurs as a result of hypertrophy and hyperplasia of the muscular layers of the pylorus, causing a functional gastric outlet obstruction. The cause is unknown. The typical age at presentation ranges from 3 to 12 weeks. It is more common in firstborn white boys and in infants with a family history of infantile hypertrophic pyloric stenosis. The classic presentation involves nonbilious vomiting (classically projectile), with an intact appetite. The emesis may become brown as a result of associated gastritis or Mallory-Weiss tear.1 The infant will eventually show signs of dehydration and weight loss, with a hypokalemic, hypochloremic metabolic alkalosis, which may evolve into lethargy and shock if not identified and treated. Palpitating an “olive” in the right upper quadrant of the abdomen is pathognomonic. A radiograph showing a dilated stomach in the proper clinical scenario, Figure 1, is suggestive. The preferred imaging study is ultrasonography. The diagnostic findings of pyloric stenosis include a hypoechoic muscle, which is thickened and measures greater than 3 mm, with a length greater than 17 mm1 (Figure 1, Figure 2). Despite the need for surgical management, initial treatment consists of correcting electrolyte abnormalities. Definitive treatment is a pyloromyotomy, although atropine has been shown to be effective if surgery is contraindicated.2

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Figure 1. Abdominal radiograph.

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Figure 2. Ultrasonography of the abdomen. Used with permission of MAJ Vincent Ball, MD, Department of Emergency Medicine, Madigan Army Medical Center, Fort Lewis, WA.

Ultrasonographic evaluation by the emergency physician for pyloric stenosis is not the current standard of care in emergency medicine, so formal radiographic ultrasonography was also obtained.